Automatic telephone system



June 29 1926. 1,590,217

J. WICKS AUTOMATIC TELEPHONE SYSTEM Original Filed March 28, 1921 3 Sheets-Shoat 1 I'LUEFLZUP- Jul-m Jnfwka June 29 1926.

. J. WICKS AUTOMATIC TELEPHONE SYSTEM Original Filed March 2 8. 1921 v 3 Sheets-Shoot 2 John Mmks Z fiZT:

June 29 1926.

J. wlcKs AUTOMATIC TELEPHONE SYSTEM ormnn Filed March 28. 1921 3 Sheets-Shoat :5

Juhn Muzks -Z. W51

Patented June 29,1926.

- UNITED STATES PATENT OFFICE.

:Ionn wIcxs, OE cIIIcAeO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0. AUTO- mtArIc E crEIc Inc, or CHICAGO, ILLINOIS, A CORPORATION or DELAWARE.

Au'roMA'rIc TELEPHONE sYs'rEiu.

Application filed March 28, 1921, Serlal- No. 456,236. Renewed November 20, 1025."

The present invention relates in general to automatic telephone systems, but is concerned more particularly with such systems as comprise main and branch exchanges; and the object of the invention is, to provide a new and improved circuit arrangement in the apparatus used by a branch exchange subscriber in calling the toll recording o-perator..

More-specifically the objects of the invention are: to provide improved circuit arrangements whereby a toll recording operator and the calling subscriber jointly control the-release of an established connection between a calling branch exchange subscriber and thetoll recording operator, and to provide improved circuit arrangements whereby a calling branch'subscriber may by moving his switch hook up and down cause the supervisory lamp in the operators cord circuit to flash, and to. accomplish these results without using a three conductor trunk line and without reversing the current flow over the two conductors of the trunk lineextending from the branch to the main exchange.

Although the invention is applicable to systems of difierent sizes, it is assumed for convenience that we are dealing with a system that has an ultimate capacity of 10,000 lines. We shall assume further that only 9,000 lines are in use and the toll recording operator occupies the position that would otherwise be taken by the tenth thousand. That is, she is reached by calling 0. The general trunking arrangement is not novel and consequently is not shown, the drawing showing only so much of the equipment as will be used to explain the novel features of the invention.

Referring to the drawings, Figs. 1, 2, and -3, when arranged in order with the corresponding lines at the. ends thereof in alignment, represent a complete connection from a calling substation A, in the branch exin Fig. 2, is also in the main office and is connected with the relay group'H Fig. 3 p in the toll'oflice by way of the trunk line'Z:

The substation A shown in Fig. 1 is an ordinary automatic substation having the usual talking and signalling instrumentalities and a calling device for controlling the automatic switches. The line switch 0, in which the line of the substation A terminates, is a rotary line switch or one in which the wipers have no normal position but move in a forward direction only.

The tone machine TM, Fig. 1 is arranged to give out four different characteristic tones. Any one of these tones may be placed upon the private normal conductor of a line switch by means of a jumper, such as the jumper 10, connected in the proper place. This tone is sent to the toll recording operator, in a manner that will be described fully hereinafter, when a call is extended to her, and indicates to her the character of the calling line or, in other words, the

, particular kind of service to which the calling subscriber is entitled.

The so called series repeater D, is used primarily to .avoid the necessity of having three conductors in the trunk line extending from the branch to the main exchange. It is understood of course, that the usual percentage trunking system is used, and, accordingly, there will be about ten trunk lines such as the trunk line X for every 100 lines in the branch exchange.

The selector E in the main exchange is mechanically of the well known Strowger type and accordingly has its bank contacts arranged in horizontal'rows or levels. The circuit of the said selector is shown complete and will be described fully hereinafter. The repeater F in the main exchange is arranged to provide a holding circuit for whatever selector seizes it and is used primarily to avoid the necessitv of having three conductcfifi's in the trunk line extending to the toll 0 cc.

The relay groupI-I in which the trunk line Z terminates in the toll ofiice has associated with it the jack J at the toll recording Operators position. The operation and utility ofthe relay group H will be explained fully hereinafter.

The cord circuit 0 shown in Fig. 3 is one that is used for answering calls coming in to the toll recording operator as well as for completing toll coninections. latter connections are well understood and have nothing in particular to do with the present invention nothing further need be said about them at this time. p

The apparatus, having been described in general, will now be described in connection with a detailed description of its operation. For this purpose it is assumed that the subscriber at substation A desires a toll connection. In order to initiate such a call he must first rall the toll recording operator who then takes care of the call and sees to it that the desired connection is established. Then the subscriber at substation A removes his receiver a circuit is completed over the line conductors 11 and 13 for the line relay 15 of the line switch C. Upon energ zing, line relay 15 closes at armature 21 a circuit for the switching relay 14 and the stepping magnet 16 in series, and at armature 26 connects the test wiper 23 to the above clrcuit at a point between the switching relay and the stepping magnet. The operation now depends upon whether the trunk line upon which the wipers of the line swltch are standing is busy or idle. If the trunk line is busy there is a ground potential on the testcontact with which the test wiper 23 s in engagement; the switching relay 14 is short circuited, and the stepping magnet 16, which interrupts its own circuit, is operated in the manner of a buzzer to advance the switch wipers in search of an idle trunk line. However, we may assume in the present case that when the call is initiated the trunk line, upon which the wipers of the line switch are standing, is idle. Under these circumstances when the, line relay 15 is energized the switching relay 14 1s not short circuited and the stepping magnet 16 is not operated because of the high resistance of said switching relay. The latter relay, however, is energized, groundsthe test wiper 23 at armature 18 and at armatures 17 and 19 disconnects the line conductors 11 and 13 from the winding of line relay 15 and from ground, respectively, and extends them by way of wipers 22 and 24. contacts 25 and 27, relay 32, upper and lowerconductors of trunk line X, and armatures 47 and 49 and their resting contacts to the upper and lower windings, respectively, of the line relay 35 of the incoming first selector E in the main exchange. Relays 32 and 35 energize in series over the calling subscribers loop. Relay 32, upon energizing, removes ground from the winding of relay 34 at armature 29' and ,at armature 29 closes the circuit of release relay 33. Upon energizing, release relay 33'grounds the release trunk conductor 30 at rmature Since these- 31. This establishes a holding circuit for the switching relay 14 of the line switch 0 as follows: from ground by way of normally closed contacts controlled by armature 31' of relay 34, armature 31 and its working contact, release trunk conductor30, test contact 26, test wiper 23, armature 18 and its working contact, switching relay 14, and stepping magnet 16 to battery. By means of the ground potential on test contact 26 and its multiples in the banks of the other line switches, the repeater D and consequently the selector E is made busy to the other line switches having-access to it. A branch of this holding circuit also extends by way of private normal conductor 12 to multiple test contacts in the banks of the connectors having access to the line of substation A, thereby guarding the line against intrusion in the usual manner.

Returning now to the selector E in the main exchange, line relay 35, upon energizmg, operates the releaserelay 36 at armature 40. Release relay 36, upon energizing. prepares the switch for operation in the usual manner.

The calling subscriber may now operatehis calling device in accordance with the digit 0 which as before explained is the digit called when connection with the toll recording operator is desired. In response to the operation of the calling device at the calling substation, the line relay of the selector E isdeenergized ten times momentarily and at each deenergization completes the followmg circuit: from ground by way of the resting contact of armature 53' of switching relay 39 and said armature, armature 40 and its resting contact, armature 41 and its working contact, slow acting series relay 37, and vertical magnet 51 to battery. By the operation of the vertical magnet the switch shaft and wipers are raised step by step until the wipers stand opposite the tenth level of bank contacts. Slow relay 37 is (mer glzed in series with the vertical magnet and retains its armature attracted throughout the vertical movement and, upon the operation of the vertical off normal contacts 43, completes a circuit for the stepping relay 38. Relay 38, upon energizing, prepares the circuit of the rotary magnet 52 at armature 46 and at armature establishes a locking circuit for itself in series with the interrupter contacts 50 of the rotary magnet 52. At the end of the vertical movement of the shaft. slow acting relay 37 deenergizes and completes the circuit of the rotary magnet 52' which thereupon energizes to advance the wipers 5860, inclusive, into engagement with the first set of bank contacts in the level opposite which they were raised. The rotary magnet also breaks, at the interrupter contacts 50, the circuit of the stepping relay 38 which deenergizes and breaks the circuit mature, and conductor 66.

accordingly energizes and at armature of the rotary magnet which thereupon deenergizes also and again closes its interrupter contacts.

The operation now depends upon whether the test contact with which the test wiper 59 is in engagement is busy or idle. If the testcontact is busy it has a ground potential on it and the stepping relay energizes again and the same cycle of operation is repeated over and over until an idle or ungrounded test contact is reached. When an idle set of contacts is reached the switching relay 39 energizes in series with the stepping relay 38 over the following circuit: from ground by way of the working contact of armature 42 and said armature, switching relay 39, interrupter contacts 50, off normal contacts 43, and stepping relay 38 to battery. Stepping relay 38, however, due to its relatively small number of turns and comparatively stiff adjustment, does not energize over this circuit. It is assumed that test contact 62 is the first one found idle. In this case, the energization of switching relay 39 switches the connection through to the trunk line terminating in the bank contacts 61-68, inclusive, and leading to the so called repeater F. The line relay 70 of the repeater F is included in a bridge across the conductors 64: and 66 as follows: from conductor 64: through armature 79 and its resting contact, upper winding of line relay 70, battery, ground, lower winding of line relay 70, resting contact of armature 95 and the said ar- The line relay 86 closes the circuit of the release relay 67. Upon energizing, relay 67 connects, at armature 77, a lead from the ringing machine RM to conductor 64 by way of armature 80 and its resting contact. This sends an audible signal back to the calling subscriber to inform him that the call is successful. It is to be understood of course that this has nothing to do with signalling the operator but is done merely to simulate the practice of giving the calling subscriber an audible signal whenever ringing current is sent out to ring the called subscribers bell. As a further result of the energization of relay 6?, armature 78 grounds the release trunk conductor 65. This ground extends back by way of the release trunk conductor 65, test contact 62, test wiper 59. and armature 48 and its working contact to the switching relay 39 of the selector E to hold the said selector in its operated position. It is understood of course that this circuit is esta lished before the slow acting release relay 36 has time to deenergize.

Returning now to repeater F we find that the energization of the line relay 7 0 not only closes the circuit of release relay 67 as before explained but also places the back bridge relay 69 in bridge of the conductors of trunk line Z at armature and its working contact. The trunk line Z as before explained extends to the ofiice in which the toll recording operator is located. The effect of placing the back bridge relay 69 in bridge of the trunk line Z, at the toll recording operators position will now be described. High resistance relay 130 is included in bridge of the conductors of trunk lineZ as follows: from the lower conductor of the said trunk line by Way of the lower left winding of repeating coil T, armature 142 and its resting contact, high resistance relay 130, and the upper left winding of repeating coil T to the up e'r conductor of the said trunk line.

in series with the back bridge the repeater F. The back bridge relay 69, however, is not energized at this time due to the high resistance of the said relay 130. Upon energizing, relay 130 closes at armature 143 the following circuit forv the line lamp L: from ground by way of the Working contact of armature 143 and said armature, armature 139 and its resting contact, and armature 132 and its resting contact to battery by way of the lamp L.

The operator upon notlng the lighted condition of the lamp L, inserts a plug of an idle cord circuit, the plug P of the cord circuit 0 for example, into the jack J and thereupon the following circuit is closed for relay 126: from ground by way of relay 126, the sleeve of jack J, the sleeve of plug P, and resistance R to battery. Upon energizing, relay 126 closes at armature 135 a circuit for relay 128 by way of the normally closed contacts cont-rolled by armature 137, and at armature 134 the said relay closes a circuit for slow acting relay 127. Upon energizing, relay 127 shifts the circuit of relay 128 so as to include armature 133 and its resting contact, and armature 137 and its working contact. At the same time that the original circuit is closed for relay-128 a circuit is also closed for relay-131 by way of armature 135 and its working contact, and armature 138 and its resting contact. Relay 127, however, is energized shortly after and at armature 138 breaks the circuit of relay 131. The effect of the energization of relay 128 will now be described. Upon energizing,'r elay 128 extinguishes the lamp L at armature 139 and closes a circuit for relay 129 at armature 140. Relay 129, upon energizing, opens a multiple point in the bridge across the conductors of trunk line X for reasons that will be hereinafter described. Returning to relay 126, the said relay, upon energizing, places a shunt around the greater part of the winding of high resistance relay 130 at armature 136. K

In the repeater F the effect of shunting most of the winding of relay 130- of relay The high resistance relay 130 is accordingly energized relay 69 in 72, resting contact of armature 90 and said armature, working contact of armature 98 further result of the energization of back bridge relay 69 is that it .closes at armature 84 and its working contact a circuit for relay 68. U on energizing, rela 68 establishes a loc ing circuit for itse f at arma- Relays 7 3 and 34 energize in series over the above traced circuit. A branch of the circuit of relay 34 also extends by way of the lower heavy talking conductor and line conductor 13 to the calling substation A and ture 81, disconnects the lead from ring1ng thence by way of the line conductor 11, and

machine RM from conductor 64 at armature 80, and at armature 79 includes the winding of relay 75 in the bridge across conductors 64 and 66. Relay 75, upon energizing, closes at armature 98 the following circuit for relay 72: from ground by way of relay and said armature, and resistanceR to battery. Upon ener izing, relay 72 closes at armature 92 a miiltiple point in the circuit of slow acting relay 76, and at armature 93 closes the following locking circuit for itself: fromcground by way of relay 72, resting contact of armature 90 and said armature, working contact of armature 93 and said armature, armature 96 and its resting contact, resting contact of armature 97 an said armature, and resistance R to battery. A further result of the energization of relay 72 is that it shifts at armature 95 the bridge across'conductors 64 and 66so as to include the winding of relay 73 instead of the lower winding of line relay 70, and closes at armature 94 the following circuit for the lower winding of line relay 7 O: froin ground by way of the lower winding of line relay 70, working contact of armature 87 and said working contact, resting contact of armature 97 and said armature, and resistance R to battery. By means of this circuit the line relay 70 is maintained energized after the bridge across conductors 64 and 66 is shifted as described. The result of the shifting of this bridge so as to include the winding of relay 73 instead of the lower winding of line relay 7 O is that current ceases to flow in conductors 64 and 66, since both conductors of the trunkl-ine X are connected to the same pole of battery. Relay 75 accordingly deenergizes and opens at armature 98 the original. energizing circuit for relay 72. Relay 72, however, remains energized over its previously described locking circuit.

In the series repeater D, the slow acting relay 32 deenergizes shortly after the current ceases to flow through it and thereupon pens the circuit of slow acting release re- 65 Y y 33 at' armature 29 and closes at armaarmature, armature 94 and its cuit in series with relay 34 of repeater D and in multiple with relay 73 of repeater F.

Relay 32 of repeater D, however, due to the high resistance of relays 34 and 75, does not receive suflicient current at this time to cause it to pull up. In the repeater F, relay 75, upon energizing, closes again at armature 98 the original energizing circuit for relay 72, while relay 73, upon energizing, opens at armature 96 the previously described locking circuit for the said relay.

The final effect of thees circuit changes, set in motion by-the inserting of the plug P into the jack J, upon the repeater D will now be described. In the repeater D, relay 34, upon energizing, closes at armature 28 a multiple point in the circuit of release relay the working contact of armature 31" and said armature and the upper or primary winding of induct-ion coil I. With this condition existing, there is a circuit completed from ground by way of the left hand winding of the transformer associated with discriminating tone machine TM, the uppermost interrupter of the said machine, jumper 10, condenser 9, private normal conductor 12, working contact of armature 18 and said armature, test wiper 23, test con tact 26, release trunk conductor 30, and thence over the previously tracedcircuit to ground by way of the upper or primary winding of induction coil 1.. The function of the discriminating tone machine TM as before stated is to cause a particular characteristic tone or series of buzzes as it might be described, to be placed on the, private normal conductor of the calling line switch, de-

pending upon where the umper 10 is placed. These fluctuations or interruptions produced by the discriminating tone machine TM are carried to the primary winding of the induction coil Iand there repeated to the secondary winding of the said induction coil which, as before stated, is at this time in bridge of the conductors of trunk line X.

The toll recording operator, having by this time thrown her listening key, K, Fig. 3, is able to hear the characteristic tone at this time and, after ascertaining to what kind of service the calling subscriber is entitled, operates the tone cut oil? key K. When the tone out 01f key K is operated a circuit is closed for relay 125. Relay 125, upon energizing, opens a point in the circuit of lamp L at armature 132 and at armature 133 opens the circuit of relay 128 at the same time closing a multiple point in the circuit of re lay 127. Relay 128, upon deenergizing, opens at armature 139 a multiple point in the circuit of relay 127, at the same time closing a point in the circuit of lamp L, opens the circuit of relay 129 at armature 140, and at armature 141 opens the bridge across the conductors of trunk line Z. Re-

lay 130 included-in the said bridge accord ingly deenergizes and opens a multiple point in the circuit of relay 127 but since the circuit of the said relay is closed atarmature 133 it does not deenergize at this time. A. moment later the slow acting relay 129 deenergizes, due to the opening of its circuit at armature 140 as previously described, and recloses the bridge across the conductorof trunk line Z. Relay 130 included in the said bridge immediately energizes again and at armature- 143 closes a multiple point in the circuit of relay 127.

The operator may now return the tone cut off key K to normal position thereby breaking the circuit of relay 125. Relay upon deenergizing, completes the circuit of lamp L at armature 132, and at armature 133 opens a multiple point in the circuit of relay 127, at the same time "closing the circuit of relay 128 by way of armature 137 and its Working contact. Relay 128, upon energizing, opens the circuit of lamp L, at armature 139, before the said lamp'has become fully lighted, at the same time closing a multiple point in the circuit of relay 127, closes at armature 141 a multiple point in the bridge across the conductors of trunk line Z, and at armature 140 closes the circuit of relay 129. Relay 129 upon energizing, opens a multiple point in the said bridge. This, however, has no function at this time.

It is now seen that whenever the tone cut off key K is operated the final result is a momentary opening of the bridge across the conductors of trunk line Z, the duration of which depends upon the time required for the slow acting relay 129 to fall back after its circuit is opened. The momentary opening of this bridge across the conductors of trunk line Z allows the back bridge relay 69 in repeater F to deenergize momentarily. Upon deenergizing, back bridge relay 69 opens at armature 83 the circuit of slow acting relay 76. It may be stated here that relay 76 in repeater F is slower to fall back than relay 12 9 in relay group H. Consequently the deenerglzation of relay 69 is not of long enough duration to allow relay 76 to deenergize. As a further result of the momentary deenergization of relay 69 it closes at armature 84 the following circuit for relay 71: from ground by way of armature 78 its working contact, armature 84 and its resting contact, and relay 71 to battery. Relay 71, uponenergizing, closes a locking circuit for itself at armature 89 by way of armature 99 and its Working contact, and at armature 90 opens the circuit of relay 72 and closes a multiple point in the circuit of the lower Winding of line relay 70. Relay 72 upon deenergizing, short circuits the winding of relay at armature 91; opens a multiple point in the circuit of slow acting relay 76 at armature 92, removes the resistance R from the circuit of the lower winding of line relay 70 at armature 94, and

at armature 95 removes the winding of relay 73 from the bridge across conductors 64 and 66 and inserts the lower winding of line relay70 therein. Relays 73 and 75 deenergize, the latter slowly on account of being short circuited. The de'energization of relay 73 has no function at this time. Relay 75 upon deenergizing, removes resistance R from the circuit of the lower winding of line relay 70.

.When the bridge across conductors 64 and 66 is thus restored, current imediately begins to flow in the subscribers loop by way of the line relay 70 and the said relay is accordingly maintained energized. Relay 32 in the repeater D now energizes and closes again l the original circuit armature 29 and at armature 29 opens the circuit of relay 34. Relay 34, upon de energizing, opens a multiple point in the circuit of release opens the bridge, secondary winding conductors of trunk line X at armature 28, and at armature 31 restores the release trunk of release relay 33 at.

relay 33 at armature 28,

including the lower or of induction coil I, of the:

conductor 30 to direct ground instead of to 7 ground by way duction coil 1. Y

The calling subscriber and the toll recording operator may now converse with of the upper winding of ineach other in the usual manner the talking circuit being outlined by ductors.

In case the call is intended for a sub- .scriber to whom connection can be extended the heavy con- 80 and its Working contact, armature 81 and a without much delay the toll recording operator functions as a regular toll operator also and completes the connection. Assuming that such is the case, she tells the calling subscriber to remain on the line while she calls the desired subscriber. To do this the operator inserts the plu in a suitable jack and thereafter takes t e suitable steps to complete the connection in any well known or desired manner.

When the connection is firmly completed, the two subscribers converse with each other in the usual manner and after the conversation is finished both subscribers replace their receivers.

When the receiver'is replaced at substationA the circuit of line relay of reeater F and rela 32 of repeater D is broken. According y line relay 70 of repeater F deenergizes and a moment later the slow acting relay 32 in repeater D deenerizes also. Upon deenergizin line relay 0 opens at armature 86 a multlple point in the circuit of release relay 67 and at armature shifts the bridge across the conductors of trunk line Z so as to include the working contact of armature 82 and said armature, resistance R, and relay 74 instead of the upper winding of back bridge relay 69, the lower winding of relag 69 is not now able to maintain the sai relay energized owing to the high resistance of relay 74 and reslstance B, and the said relay accordingly deenergizes and, at armature 83 opens the circuit of slow relay 76. Relay 74,

however, energizes and at armature 97 closes a circuit for relay 72. Relay 7 2, upon enerizing, closes at armature 92 a multiple point 1n the circuit of slow acting relay 76 before the said relay has had time to deenergize; substitutes relay 73 for the lower winding of line relay 70 at armature 95 and at armature 91 removes the short from the winding of relay 75.

In the repeater D, relay 32 upon deenergizing, opens at armature 29 the circuit of release relay 33 and at armature 29' closes the circuit of relay 34 and since the circuit changes are made as described in the repeater F the two relays 34 and 73 energize in series with each other over a circuit previously traced. The energization of relay 73 has -no function at this time. Relay 34 upon energizing, closes again the circuit for release rela 33 at armature 28 before the said relay as had time to deenergize and thus maintains the line switch C in its operated position. It is now seen that, contrary to the usual practice, even though the subscriber at substation A has replaced his receiver the connection is not released. The function of this holding up of the connection will be described fully hereinafter.

The effect produced in the relay group H by the inserting of resistance R and relay 74 in the bridge across the conductors of trunk line Z in place of. the upper winding of back bridge rela 69, as before explained, Wlll now be described. When the bridge across the said conductors in the repeater F is thus changed the resistance is raised 'sufii- 'ciently to allow the relay 130 the lower part of the winding of which is 1ncluded in the bridge of these conductors at the relay group H, to deenergize. Upon deenergizing, relay 130 o ens the circuit of slow acting relay 127. t may be stated here that while relay 127 is slow releasing it is onl slightly so. That being the case, relay 12; deenergizes almost immediately and thereupon closes at armature 138 a circuit for relay 131. Upon energizing, relay 131 connects battery and ground by way of the resistance R and B, respectively, working contacts of armatures 145 and 146, and said armatures, up er and lower right windings of the repeatlng coil T, jack J, plug P, and thence by way of the upper and ower springs of key K and their resisting contacts, normally closed contacts controlled by the upper and lower springs of key K to supervisory relay 150. Supervisory relay 150, upon energizing, closes at armature 151 a circuit for the lamp L, and the said lamp becomes li hted.

The operator, upon notin the ighted condition of lamp L, knows t at the oonversation is finished and that the subscriber at substation A has hung up his receiver. Accordingly she removes the plug P from jack J thereby opening the circuit of relay 150 and also of relay 126 in relay group H. Relay 150 upon deenergizing extinguishes the lamp L. Relay 126 upon deenergizing, opens at armature 135 the circuits of relays 128 and 131 and the two relays accordingly deenergize. Upon deenergizing, relay 128 opens at armature 141 the bridge across trunk line Z and, at armature 140, opens the circuit of relay 129. Relay 129 upon deenergizing, closes again the bridge across trunk line X.- All the relays in relay group H are now deenergized.

When relay 126 falls back, armature 136 includes the upper portion of the winding of high resistance relay 130 in the bridge across the conductors of trunk line Z, thereby raising the resistance of the bridge sufficiently to cause relay 74 in repeater F to deenergize. The quick deenergization of the said relay is assured by the momentary opening of the bridge by the combined action of relays 128 and 129 as explained.

Upon deenergizing, relay 74 opens at armature 97 the circuit of relay 72. Relay 72, upon deenergizing, shifts, at armature 95, the bridge across conductors 64 and 66 back to its normal path which includes the lower winding of line relay 7 0 instead of the winding of the relay 73. Relays 73 of repeater F and 34 of repeater D now deenergize. As

a further result of the deenergization of relay 72 the circuit of slow acting relay 76 is opened at armature 92. Upon deenergizing relay 76 opens at armature 99 the circuit oi relay 71. Relay 71 deenergizes but this deenergization has no particular function at this time. Upon deenergizing, relay 76 also opens at armature 100 the circuit of slow acting release relay 67. Upon deenergizing, relay 67 removes ground from release trunk conductor 65. Relay 68' immediately deenergizes and at armature 82 opens the circuit of relay 74 so as to prevent a continual flow of current through the said rela the relay being already in a dcenergize condition. All the relaysof repeater F are now deen ergized. When ground is removed from release trunk conductor 65, by the deenergization of relay 67 as explained, the selector E releases in the usual manner.

Returning now to relay 34 of repeater D, that relay, upon deenergizin opens at armature 28 the circuit of re ease relay 33. Upon deenergizing, relay 33 removes ground from release trunk conductor 30 at armature 31. This opens the holding circuit for line switch C and switching relay l4 accordingly deenergizes. The entire connection is now released.

In order to show how a calling subscriber can flash the supervisory signal in the operators cord circuit to attract the attention of the operator we shall assume that during the time the connection just described is established the subscriber atsubstation A desires for some reason to attract the attention of the operator. It has been-shown already how the replacing of the receiver on the hook results finally in the llghting of lamp L of the cord circuit 0. 'Now, if the subscriber immediatel removes the receiver again the hereinbe ore described circuit for relay 7 5 is closed in series with relay 34 and in multiple with relay 73., It may be stated here that, owing to the high res stance of relays 34 and 75 the current flow1n 1n the upper winding of line relay 7 0 at thlstlme is insuflicient to operate the said relay. Relay 75, upon energizing, closes at armature 98 a circuit for the lower winding of line relay 70. Line relay 70, upon energizing, shifts the bridge across the conductors of trunk line Z so as to include the upper winding of back bridge relay 69 instead of resistance R and relay 74. Relay 69 immediately energizes and at armature 83 closes a multiple point in the c rcuit of relay 76. Relay 74 upon deenerg zing, opens the circuit of relay 72. Relay 72 upon deenergizing, short circuits relay 7 5 at armature 91, and at armature 95 removes relay 7 5 from the bridge across conductors 64 and 66 and reinserts the lower winding of relay therein. Relay 75 upon deenergizing removes resistance R from the circuit of the lower winding of relay 70 leaving the said relay bridged across the conductors 64 and 66. The current flow in the subscribers loop 1s-now increased to normal and relay 32 of repeater D accordingly energizes and 70 opens the circuit of relay 34 and closes a multiple point in that of release relay 33. Relay 34 upon deenergizing opens at armature 28 a multiple point 1n the circuit of relay 33. 75

Returning now to relay 69 of repeater F, when the upper winding of the said relay is reintroduced into the bridge across the conductors of trunk line Z at armature 85 of relay 70, the current flow in the trunk line Z is increased sufliciently to cause relay 130 in relay group H to energize again. Ufpon energlzin relay 130 closes the circuit 0 relay 127. Relay 127 upon energizing, opens at armature 138 the circuit of relay 131. Relay 131'upon deenergizing, opens at armatures 145 and 146Vthe circuit of relay 150 of cord circuit 0. Relay 150 upon deenergizing, extinguishes the lamp L. This lighting and extinguishing of lamp L is repeated each time the subscriber at substation A slowly moves the switch hook up and down thereby attracting the attention of the operator.

In the call that has been hereinbefore described, it was assumed that the connection could be extended quickly to the called subscriber. In case a call is made to the toll recording operator that is intended for a subscriber to whom connection cannot be extended quickly, the toll recording operator, after obtaining the desired information, tabulates the information received on .a

ticket or in any other well known or preferred manner and either completes the connection later or passesthe ticket to a regular toll operator depending of course upon the method of operation employed by the operating company.

After the desired information is obtained the toll recording operator removes the plug P from the jack J and the subscriber at substation A replaces his receiver andthe re lease of the connection takes place.

The utility of having the release of the connection controlled by the toll recording operator is explained as follows: Many times it is necessary for the toll recording operator to check up on the calling subscriber to find out whether or not the number he gives for his is the correct one, in order to be sure that she does not take a charge against the wrong subscriber. It is desirable to do this without the knowledge of the calling subscriber. In order to make this check, the toll recording operator calls the number given by the calling subscriber as his. If she gets the busy signal she takes it for granted that the number given is correct.

If the calling subscriber were able to release the connection he might do so before the operator is able to make the proper check with the result that instead of getting the busy signal the operator obtains connection with his line again thereby causing his bell to be rung and the subscriber is caused the trouble (if answering a false call. With the release of the connection controlled by the operator, however, this is impossob'le for she does not release theconnection until after she has obtained the desired information.

Having described and ascertained the features of the invention what is considered to be new and desired to have protected by Letters Patent will be pointed out in the ap-- pended claims.

What I claim as my invention is:

1. In an automatic telephone system, a branch exchange, a main exchange, a toll oflice, a two conductor trunk line connecting the branch and main exchanges, a two conductor trunk line connecting the main exchange with the toll ofiice, arepeater in each trunk line, an inductive winding in the second repeater for supplying talking current to a calling line, a signal'at the operators position, means whereby the calling subscriber can decrease the current flow in the second named trunk line, and means responsive to the decreased current flow for operating said signal.

2. In an automatic telephone system, a toll operators position, a trunk line comprising two inductively connected sections terminating at said position, switching mechanism whereby a calling subscriber can extend a connection to said trunk line to connect with the operator, a supervisory cir-' cuit including the two talking conductors of the second section, a relay controlled over the talking conductors of the first section and deenergized when the calling subscriber hangs up his receiver, means controlled by said relay for altering the said supervisory circuit to increase the resistance thereof, a relay included in the altered circuit and energized thereover for preventing the release of said switching mechanism, a supervisory relay at the operators position included in the supervisory circuit and deenergized when the resistance thereof is increased, and means whereby the operator can further increase the resistance of said supervisory circuit to deenergize said second relay to release the said switching mechanism.

3. In an automatic telephone system, a toll operators position, a trunk line comprising two inductively connected sectionsterminating at said position, switching mechanism whereby a calling subscriber can extend a connection to said trunk line to connect with the operator, a cord circuit at the operators position for connecting the trunk line with another line, a supervisory circuit including the two talking conductors of the second section, a relay controlled over the talking conductors of the first section and deenergized when the calling subscriber hangs up his receiver, means controlled by said relay for altering the said su ervisory ycircuit to increase the resistance t ereof, a relay included in the altered circuit and energized thereover for reventing the release of said switching mec anism, a supervisory relay at the operators position included in the su ervisory circuit and deenergized when t e resistance thereof is in reased, a supervisory lamp lighted when t e supervisory relay deenergizes to give the operator a disconnect signal, and means operated automatically when the operator pulls down the connection for further increasing the resistance of said su ervisory circuit to deenergize the second relay to restore said switch-. ing mechanism.

4. In an automatic telephone system, an operators position, means including automatic switches and a trunk line whereby a calling subscriber can extend a connection to said operators position, means whereby the calling subscriber can decrease the current flow in said trunk line to signal the operator, and means whereby the operator can further decrease the current flow in said trunk line to release said switches.

5. In an automatic telephone system, an

tomatically and momentarily opening said bridge responsive to the actuation of said key, and means responsive to the opening of said bridge for rendering said signal inaudible.

6. In an automatic telephone system, an operators position, a repeater, a trunk line comprising only two conductors extending from the repeater to the operators position,

means including automatic switches whereby a calling subscriber can extend a connection to said repeater, a signal at the operators position, circuit arrangements such that the opening of the line circuit by the replacement of the calling subscribers'receiver before the operator answers will release the said switches, and circuit arrangements ef; fective after the operator answers for permitting the calling subscriber to flash said signal by moving the receiver hook up and down.

- 7. In an automatic telephone system, an operators position, a repeater, a. trunk line comprising only two conductors extending from the repeater to the operators position,

' means including automatic switches whereby the continued closure ofthe line clrcuit atthe calling substation, and circuit arrangements effective after the operator answers whereby the opening of the line circuit at the substation by the re lacement of'the receiver will cause said signal to be operated while still maintaining the connection intact.

' 8. In a telephone system, an operators position, a trunk extending to said position, means including an automatic-switch whereby a callin subscriber can extend-a connection to sai position by way of said trunk, a holding circuit for said switch established when connection is extended to said trunk,

circuit arrangements such that the opening of the line c1rcuit by the calling subscriber before the operator answers opens said holding circuit, and means responsive. jointly to the answering of the operator and to the opening of the line circuit by the calling subscriber and controlled over a talking conductor of said trunk for rendering the openmg of the line circuit by the calling subscriber inefiective to open said holding circuit.

9. In a telephone system, an operators position, a trunk extending thereto, means including an automatic switch whereby a callin subscriber can extend a connection to sai position by way of said trunk, a release circuit including a conductor of said switch and a conductor of said trunk in se-' ries, circuit arrangements such that the opening of the line circuit by the calling subscriber prior to the answering of the operator results in said release circuit being altered to eifect the release of said switch, and means responsive jointly to the answering of the operator and to the openin of the line circuit by the calling subscri er and controlled over a talking conductor of said trunk for rendering the opening of said line circuit by the calling subscriber inefl'ective to bring about the release'of said switch.

10. In a telephone system, an automatic switch, a trunk, means including said switch and trunk in serial relation for setting up a desired connection, means for releasing said switch at the termination of the conversation, and holding means for closing a circuit including one talking conductor of said trunk and excluding the other talking conductor thereof to render said releasing means inoperative,said holding means being rendered effective responsive to an attempt to releasesaid switch. s

11., In a telephone system, an automatic switch, a trunk, means including said switch and said trunk in serial relation for setting up a desired connection to a manual switchboard, means for releasing said switch at the termination of the conversation, and holding means applied by an o erator at said switchboard for closing), su ject to the abandonment of the call y the calling party, a circult lncluding one talking conductor of said trunk line and excluding the other talking conductor thereof to render said releasing means inoperative.

1 2. In a telephone system an automatic sw1tch, a trunk, means including saidswitch and said trunk in serial relation for setting up a desired connection to a manual switchboard, means for releasing said switch at the termination of the conversation, and holding means applied by an operator at said switchboard for closing a holding circuit including. one talking conductor of said trunk and excludin the other talking conductor thereof to ren er said releasing means inoperative, said holding meansbeing rendered effective responslve to an attempt to release said switch.

l3. In a telephone system, a manual switchboard, a battery, an automatic switch, two trunk lines, means including said automatic switch for setting up a connection to said switchboard including said trunk lines in serial relationshi means for signalling the operator responsive to the completion of said connection controlled over the two conductorsof the first trunk line in series, said conductors being connected to opposite terminals of said battery, and means rendered efiective by the response of the operator at said switchboard and controlled over the two conductors of the second trunk linein series to disconnect one of the conductors of the first trunk line from the associated terminal of said battery and to connect it to the other terminal of said battery.

14. In a telephone system, a manual switchboard, a battery, an automatic switch, a trunk line, means including said automatic switch for setting up a connection to said switchboard including said trunk line, .means for signalling the operator responsive to the completion of said connection over the two conductors of said trunk line in series, said conductors bein connected to opposite terminals of said attery, means rendered effective by the response of the operator at said switchboard to disconnect one of the conductors of-said trunk line from the associated terminal of said battery and to conplaced his receiver, and means for signalling the operator in case the calling subscriber replaces his receiver while both of said conductors are connected to the same pole of battery.

15. In a telephone system, an automatic switch, a manual switchboard, a trunk line, means including said automatic switch and said trunk line for setting up a connection to said switchboard, means controlled from said switchboard for placing a holding condition on said trunk line, a local holding conductor at the outgoing end of said trunk line for maintaining said automatic switch operated, means responsive to thesaid holding condition for placing a holding potential on said holding conductor, and means for signalling the operator at said switchboard in case the calling party abandons the connection while said holding condition is on said trunk line. i

16. In a telephone system, an operators switchboard, an automatic switch, a trunk line, means includin said switch and said trunk line for extending a connection from a calling line to said switchboard, means at said switchboard for maintaining said switch operated by means of a circuit including one talking conductor and a. separate return conductor, a supervisory signal at said switchboard, and means controlled from the calling line over the other talking conductor for operating said signal.

17. In a telephone system, an automatic switch, a trunk line, an operators switchboard, means including said switch and said trunk line for setting up a connection from a callin line to said switchboard, means rendere eifective by the response of the operator at said switchboard for establishing a holding circuit for said switch over the two conductors of said trunk line in parallel, means controlled by the operator at said switchboard for opening said holding circuit, and means controlled by the calling subscriber prior to said opening of theholding circuit for signalling the operator over the established connection.

18. In a telephone system, an automatic switch, a trunk line, an operators switchboard, means including said switch and said trunk line for settin up a connection from a calling line to sa1d switchboard, means rendered effective by the response of the operator at said switchboard for establishing a holding circuit for said switch over the two conductors of said trunk line in parallel, and means controlled by the calling station for signalling the operator at said switchboard by opening the branch of said holding circuit over one conductor, while said switch is maintained operated by that branch of the holding circuit that includes the other conductor. 7

19. In a telephone system, an automatic establishing a holding circuit for the first switch, a trunk line, a second automatic switch, a manual swltchboard, means controlled from a calling line for operating the first named automatic switch to extend a connection to. said trunk line, and for operating said second automatic switch over the two conductors of said trunk line in series to extend a connection to said switchboard, means controlled from said switchboard for automatic switch over the two conductors of said trunk lines in parallel, and means controlled by the calling arty for si alling the operator at said lswitchboar by opening the branch of said holding circuit including one conductor of said trunk line, while the first automatic switch is maintained operated by that branch of the holding circuit which includes the other conductor of said trunk line.

20. In a telephone system, an automatic switch, a trunk line, a second automatic switch, a manual switchboard, means controlled from a calling line for operating the first named automatic switch to extend a connection to said trunk line, and for operating said second automatic switch over the two conductors of said trunk line in series to extend a connection to said switchboard, means controlled from said switchboard for 9 establishing a holding circuit for the first automatic switch over one conductor of said trunk line and over a return circuit se arate from the other conductor of said trun line, and means controlled by the calling party for signalling the operator at said switchboard, while the'first automatic switch is maintained operated over said holding circuit.

- 21. In a tele hone system, an automatic switch, a trun line, a second automatic switch, a manual switchboard, means controlled from a calling line for operating the first named automatic switch .to extend a connection to said trunk line, and for operating said second automatic switch over the two conductors of said trunk line in series to extend a connection to said switchboard, means controlled from said switchboard for establishing a localholding circuit for the second automatic switch and for establishing a holdin circuit for the first automatic swltch over t e two conductors of said trunk line in parallel and means controlled by the calling party for signalling the o rator at said switchboard by opening the ranch of said holding circuit including one conductor of said trunk line, while the first automatic switch is maintained operated by that branch of the holding circuit which includes the 1 5 other conductor of said trunk line. L

22. In a tele hone system, an automatic switch, a trun line, a second automatic switch, a manual switchboard, means controlled from a calling line for operating the first named automatic switch to extend a connection to said trunk line, and for operating said second automatic switch over the two conductors of said trunk line in series to extend a connection to said switchboard, means controlled from said, switchboard for settin up a local holding circuit for said second automatic switch and for establishing a holding circuit for the first automatic 1' switch over one conductor of said trunk line and over a return circuit separate from the other conductor of said trunkline, and means controlled by the calling party for si ailing the operator at said switchboard,

w 1c the first automatic switch is main- 15 tained operated over said holding circuit.

In witness whereof, I hereunto subscribe my name this 23d day of March, A. D., 1921.

JOHN WICKS. 

